Ghosting / Double Tone / Cone Cry Question

[Electric_Wizard]

Hello there.

It recently came to my attention that many rock songs of the 70s has that "undertone", "ghost" sound to it, hidden undeneath it all, that sounds like an octave below, but it's not really there.

I've been looking around on how to emulate it in a pedal or whatever, but i have not managed to find any pedal that does it, besides revivaldrive, which you can see here :

I don't want to recriate revivaldrive, I just want the "ghosting" effect, because i am trying to get close to the Black Sabbath sound.
You can find more about ghosting here (minute 5:51)

in another video, they call it the "Cone Cry", or "Ring Modulator" tone :

Is there any schematics that would help me recriate this sound?

Thanks In Advance & Best Regards

[Fancy Lime]

Simple envelope controlled LFO should do it, no?

Andy

[ElectricDruid]

Welcome Electric Wizard, Electric Druid here!

If I understood what they're saying about how the sound is created, it's some weird modulation in the output stage caused by the power supply ripple. So you should get close with a 50 or 60Hz oscillator feeding a tremolo or a ring mod.

The fact that the Revival Drive has a switch that lets you choose which frequency you use suggests to me that they're doing it by some similar means. After all, if you've got a modulation oscillator, it would be very easy to add a switch to select between 50 and 60Hz.

I'd start with a basic '3080 ring mod circuit, not worry too much about the balance (if it's out of balance, it's more like a tremolo) and feed 50Hz sine wave in the other side and see how close you can get.

[iainpunk]

welcome to the forum.

Simple envelope controlled LFO should do it, no?

Andy

no, it comes from the clipping. the positive clipping threshold is not stable, but a bit of AC modulates that threshold. its always the local mains frequency that is created due to poor power supply design.

i'll draw up something in flastad to explain visually,

cheers, Iain

[iainpunk]

just to get the idea across

[Electric_Wizard]

Thanks for the replies!
I might be trying something soon.

One more thing : Can it happen if i plug my preamp pedal with 18v?

[iainpunk]

Thanks for the replies!
I might be trying something soon.

One more thing : Can it happen if i plug my preamp pedal with 18v?

most probably not, it needs AC ripple on the power rail and also clip to rails, and your 18v is probably a regulated supply. (doesn't have ripple)
another option is a dedicated oscillator that modulates the clipping threshold like in the schematic i posted,

cheers, Iain

[danfrank]

"Ghosting" is a layman's term for intermodulation distortion, a very bad thing in hi fi amps but (maybe) a good thing for old tube guitar amps. Usually caused (like the Brit said) by the power line frequency modulating whatever is being played through the amp. Most common cause is an old tube amp with dry/leaky power supply caps. PRR can give a much better explanation of what's involved.
Anyway, I'd get a 50 or 60Hz oscillator (op amp) and somehow combine it in very small quantities with whatever audio signal you want to manipulate. A ring mod might come close but the 50-60Hz signal has to very weak.
In the Rick Beato video, I cant hear it, and that's the general problem of ghosting. People on the stage performing can hear it, but for the most part nobody else does. So, what's the point?
I'm not trying to be a smart ass here, I was just wondering...

[iainpunk]

come to think of it, the line frequency gets doubled in the rectifying process, so its probably 100 and 120 Hz.
the tone is created by a wiggling clipping threshold, its like tremolo, but with clipping. in the schematic i posted, the top side is clipped against the triangle wave, creating the same kind of effect. the bottom is just clipped with diodes, this is realistic because only the V+ rails has ripple in a tube amp, the ground is stable.
the ghost note is not there if there is no clipping going on

cheers, Iain

[willienillie]

come to think of it, the line frequency gets doubled in the rectifying process, so its probably 100 and 120 Hz.

Yes if it's from B+, almost always full-wave rectified.  Bias supply in fixed-bias guitar amps is usually half-wave rectified, and frequently under-filtered, so that can result in 50/60Hz noise*.  There can be "ghost notes" from circuit instability also, but that's a more complicated topic.  I had a Tube Screamer clone that would do it too, give that sub harmonic that would go down in pitch as you bent up, or vice versa.  "Cone cry" is a speaker thing, totally different.

*Edit:  I should also mention the filament supply, probably responsible for more 50/60Hz noise than the bias supply, but that depends on the amp in question.

[Vivek]

come to think of it, the line frequency gets doubled in the rectifying process, so its probably 100 and 120 Hz.
the tone is created by a wiggling clipping threshold, its like tremolo, but with clipping. in the schematic i posted, the top side is clipped against the triangle wave, creating the same kind of effect. the bottom is just clipped with diodes, this is realistic because only the V+ rails has ripple in a tube amp, the ground is stable.
the ghost note is not there if there is no clipping going on

cheers, Iain

Is "wiggling clipping threshold" same or similar to "Steady threshold level but wiggling signal level" ie can we just have a 100 Hz tremolo that changes the signal level to maybe 120% - 80% and back at 100 Hz  and that goes to a clipper?

ie LDR in feedback loop maybe, getting modulated by an Oscillator ?


like clipping an Amplitude modulated signal ?

[iainpunk]

Is "wiggling clipping threshold" same or similar to "Steady threshold level but wiggling signal level" ie can we just have a 100 Hz tremolo that changes the signal level to maybe 120% - 80% and back at 100 Hz  and that goes to a clipper?

ie LDR in feedback loop maybe, getting modulated by an Oscillator ?


like clipping an Amplitude modulated signal ?

no, no and no.
1) one side of the wave stays at the same threshold, the other doesn't, this results in an actual addition of the 100Hz to the signal, as well as the modulation
2) the threshold wiggles, not the gain. this results in only being present while clipping, not clean.
3) tremolo does change the volume BEFORE clipping, changing the perceived volume and gain IN phase. the threshold wiggle slightly changes both the perceived gain and the actual volume out of phase (less gain when it gets louder and more when it gets quieter)
4) i refer to the schematic i posted before, it changes one side of the clipping with the oscillator while the other side stays put, i recommend making the oscillator variable (both in amplitude and frequency) to change the depth and match it to the key of the song.

cheers, Iain